1. Field of the Invention
This invention relates in general to test circuits for determining the phase modulation distrubances of a measuring signal which passes through a test object.
2. Description of the Prior Art
Phase variation has previously been measured at measuring points which lie in range of the carrier frequency operated portions or stages of a carrier frequency transmission system and the signal being measured is picked up and converted with a carrier frequency heterodyne receiver of a level measuring apparatus and is converted into the original frequency position and fed in at the low frequency input and then is evaluated by means of measuring apparatus operating in the low frequency range. Such prior art systems require expensive apparatus and numerous operating stages and settings of the interconnected devices which make the measurement time lengthy and very expensive.